romenskiy2012/curl
1
0
Fork 0
mirror of https://github.com/curl/curl.git synced 2026-05-06 03:37:37 +03:00
Code Issues Projects Releases Packages Wiki Activity

libssh/sftp: fix resume corruption by avoiding O_APPEND with rresume

Browse source 
Opening the remote file with O_APPEND while attempting to resume causes
all writes to be forced to EOF on servers/implementations where O_APPEND
semantics override a prior seek(). As a result, sftp_seek64() is ignored
and the resumed data is appended, duplicating/corrupting the file.

Fix by:
- Using O_WRONLY (without O_APPEND) when resume_from > 0.
- Skipping the seek entirely if remote_append mode is requested.

Closes #18952
This commit is contained in:
Joshua Rogers 2025-10-09 06:03:08 +08:00 • committed by Daniel Stenberg
parent c0a279a8e9
commit 391e3fbeec
No known key found for this signature in database
GPG key ID: 5CC908FDB71E12C2
1 changed files with 14 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

22
lib/vssh/libssh.c
View file

@ -1154,12 +1154,18 @@ static int myssh_in_UPLOAD_INIT(struct Curl_easy *data,
}
}
if(data->set.remote_append)
/* Try to open for append, but create if nonexisting */
flags = O_WRONLY|O_CREAT|O_APPEND;
else if(data->state.resume_from > 0)
/* If we have restart position then open for append */
flags = O_WRONLY|O_APPEND;
if(data->set.remote_append) {
/* True append mode: create if nonexisting */
flags = O_WRONLY | O_CREAT | O_APPEND;
}
else if(data->state.resume_from > 0) {
/*
* Resume MUST NOT use O_APPEND. Many SFTP servers/impls force all
* writes to EOF when O_APPEND is set, ignoring a prior seek().
* Open write-only and seek to the resume offset instead.
*/
flags = O_WRONLY;
}
else
/* Clear file before writing (normal behavior) */
flags = O_WRONLY|O_CREAT|O_TRUNC;
@ -1189,8 +1195,8 @@ static int myssh_in_UPLOAD_INIT(struct Curl_easy *data,
}
/* If we have a restart point then we need to seek to the correct
position. */
if(data->state.resume_from > 0) {
position. Skip if in explicit remote append mode. */
if(data->state.resume_from > 0 && !data->set.remote_append) {
int seekerr = CURL_SEEKFUNC_OK;
/* Let's read off the proper amount of bytes from the input. */
if(data->set.seek_func) {